1. Field of the Invention
The present invention relates to a semiconductor device comprising a control electrode containing metal or metal silicide.
2. Description of the Related Art
Recently, as a LSI is becoming higher in density, a capacitor insulating film and a gate insulating film are going on thinning. In order to avoid increasing of leakage current caused by the thinning, attempts such as introducing a three dimensional structure cell or an insulating film having a high dielectric constant are made.
For example, in the case of a flash memory, a high dielectric constant film, such as an ONO film (three-layer lamination film of silicon oxide film/silicon nitride film/silicon oxide film) or an Al2O3 film is used as an insulating film (inter-gate electrode insulating film) provided between a floating gate electrode and a control gate electrode, and an area of the inter-gate electrode insulating film is increased by introducing the three dimensional structure to the memory cell, thereby, an electric field applied to the inter-gate electrode insulating film is suppressed and the increasing of the leakage current is suppressed.
However, according to the thinning of the inter-gate electrode insulating film accompanied with the further miniaturization (subsequent to the half-pitch 32-nm generation), the following problem is becoming not negligible. That is, the electric field concentrates at the corner of the lower part of the control gate electrode, and it causes problems that a break down voltage of the inter-gate electrode insulating film at the lower part corner is insufficient and the increasing of the leakage current is not negligible (Jpn. Pat. Appln. KOKAI Publication No. 2000-200841).